GE defrost problems - question

defrost system kit installed 10-2007 (heater thermostat ?)
mainboard installed 11-2007

freezer not cold enough, ice melts, etc -usually unplugging and allowing to defrost manually and dry out solved issue for several months

on latest occurance after performing some of the troubleshooting procedures found the following;

22 ohms on the heater - should be OK?
voltage check for fan motor constant 13V on red to white
white to yellow started at 5-6 volts (after turning freezer temp control to 5 and then connecting voltmeter) and steadily increased to over 9V before I disconnected meter

Fan will not start spinning on it’s own. If I hold the blade I can feel the magnetism and will sping after it’s touched.

Is the motor the issue? or the driver board?

Whenever the system turns off the fan it will not start turning again without touching (or spinning) it. Frequency of the fan is annoying to the ears. Is the voltage supply correct or woiud one need an oscilloscope to check the waveform? or is the fan motor the culprit?

Voltage should be DC.

Here is a link just posted by applianceman that may be helpful.
http://www.appliance-repair-it.com/refrigerator-fan-motor.html

Sounds like it is probably just the motor.
Your heater seems OK to me.
You also have a defrost thermostat in this circuit,clipped to the evaporator coils. It is normally 0 ohms when frozen, it opens just above freezing. Also if it looks bulged it should be replaced.
Unless the evaporator coils are iced/frosted up to the point where the evaporator fan cannot pull air through them you probably do not have a defrost problem.

It is possible that perhaps some moisture has gotten into the motor’s bearings and is causing the fan to stall when the freezer cools down.

The South Jersey schematic shows a 220 to100 Hz square wave to J2 pins 3 and 1. Usually, if the motherboard is acting up, this signal will get distorted and cause the evaporator fan motor to make bad/annoying sounds, usually replacing the motherboard will fix it.
Also, there should be a slinger/umbrella piece on the motor shaft to prevent moisture from getting in the motor bearings, might want to check for this.

Defrost problems are back. This model has 2 temp sensors, one at the bottom outside the coils enclosure and one mounted to the top coil. Additionally there is a defrost thermostat mounted near the top. Should I replace all 3 and the heater at this point or trial and error?

Usually you can see a blown heater, it will have an open spot in it. The thermisters are cheap enough, i would replace them all.

Thanks for the reply. I’ve replaced the upper thermistor. I’t s resistance was all over the place. The upper limit heat thermostat had been replaced. Hoping for the best.

Thanks Again,
Paul

Good news.